<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <input type="text" name="age" size="3" onChange="validate(this, 18, 99);" />

    <script>
      function validate(obj, lowval, hival) {
        if (obj.value < lowval || obj.value > hival)
          console.log("Invalid Value!");
      }
      document.querySelector('input').addEventListener('change',validate(this, 18, 99))
    </script>
  </body>
</html>

<!-- 必须要监听呀 -->
